Plate-shaped or tubular insulating material

ABSTRACT

The invention relates to an insulating material in the form of plates or tubes, comprising a layer of expanded rubber ( 11 ). The main surface ( 12 ) of said layer is the surface which comes into contact with an object to be insulated, and a protective layer is adhesively connected ( 16 ) to the opposite main surface ( 13 ) of said layer. In order to increase the flame resistance, said protective layer consists of a mat-shaped glass fibre material ( 14 ) which is externally coated by a metal or a polymer ( 15 ).

[0001] The invention relates to an insulating material in the form of plates or tubes according to the precharacterizing portion of claim 1.

[0002] An insulating material of this type is known from European patent application 0 916 483 A2, wherein the plastic foam of the basic layer is polypropylene or polyethylene foam, while the outer coating consists of a protective layer resistant to tearing, for example of a mesh-structured foil made of fabric. The intermediate layer comprising the non woven glass fiber fabric shall in the event of a short exposure to heat or fire protect the fire-sensitive plastic foam from being destroyed.

[0003] From German patent application 30 30 120 A1, an insulating material in the form of a tube is known, the tube having a basic layer consisting of a non inflammable material, like mineral wool or glass fiber, wherein on the basic layer a protective layer is applied which is formed by two aluminium foils, inbetween which foils a glass fiber armouring having a large mesh size is inserted. This construction of the protective layer is intended to improve the fire-proofness of the insulating material.

[0004] From U.S. patent application Ser. No. 4,121,958 A, an insulating material is known, having a basic layer of a closed cell foam, preferably polyurethane foam, on which layer on one side a porous layer of fabric or paper, then a network of glass fiber strands and externally a metallic foil may be applied. In order to connect the layer elements, an adhesive is used, showing a high flame retardancy. Hereby, the porous layer of fabric or paper is mandatory in order to achieve a sufficient bonding on the polyurethane layer. The insulating material is a basically rigid board.

[0005] From German patent application 38 10 996 A1, a flat form for round compensators of high energy installations is known, said form consisting of two layers of an elastomeric material, like fluor rubber, inbetween which layers two systems for reinforcement are arranged, wherein one is a knitted fabric consisting of steel or glass and the other is made of steel cord, cord fibers or of a monofil material.

[0006] From German utility model 77 16 580 U, it is further known a jacket for an insulated pipe, said jacket consisting of a glass fiber fabric, which externally is having a coating of acrylic resin.

[0007] UK patent application 2 283 798 A discloses an insulating material in the form of a pipe made of a plastic foam, said foam having an outer layer of a fabric-like material which consists of glass fiber coated with silicone.

[0008] In order to increase the flame resistance, it is further known to add to mixtures for the production of expanded rubber, apart from the required flame-protecting agents, additional, in particular halogenated flame-protecting agents. These additional flame-protecting agents may in the event of a fire lead to the emission of toxic gases.

[0009] The task of the present invention is to provide an insulating material mentioned in the first section of the specification such that its mechanical stability will be increased without the addition of additional flame-protecting agents, while at the same time an improved flame resistance will be achieved, or that it will be classified in the same fire classification, while at the same time a reduction in the required flame-protecting agents will be accomplished.

[0010] This task is solved by the features as indicated in claim 1.

[0011] When the coating is of metal, it preferably consists of aluminium or copper. If it is a polymer, it advantageously consists of polyurethane, polyvinyl acetate, polyvinyl chloride or an anorganic or organic silicone compound, like silicone rubber.

[0012] The coating may be generated by means of gluing on a foil, or when the coating is to be particularly thin, by sputtering or evaporation. In case of gluing, it is of advantage to use a flame-retardant adhesive.

[0013] When the plates or the tubes are to be connected at joints, overlappings may be provided at the respective sides, wherein at a joint, where for installation purposes the tubes were slit in parallel, the outer layers may in the area of the slit be also extending beyond a circumferential section in an overlapping manner.

[0014] Advantageously, the expanded rubber consists of acrylonitrile-butadiene rubber (NBR), ethylene propylene-diene monomer (EPDM) rubber, chloroprene rubber (CR, CSM), silicone rubber or of mixtures of acrylonitrile-butadiene rubber with polyvinyl chloride.

[0015] On account of the glass fiber material layer, being externally coated with a metal or a polymer, the insulating material achieves without the use of halogenated flame-protecting agents, which agents in the event of a fire would lead to the generation of toxic gases, unexpectedly high fire class ratings, while at the same time a substantially improved mechanical stability and good flexibility is achieved. Hereby, the usual heat insulating properties are maintained. In comparison with commonly used insulating materials, cheaper rubbers or a reduced amount of the chemical flame-protecting agents may be used, while at the same time the fire class standard can be maintained.

[0016] When an insulating material according to the state of the art and consisting of a layer of expanded rubber, which is on one side by means of a flame-retardant adhesive adhesively connected with a protective layer, for example in the form of an aluminium foil, is under predefined test conditions on the side of the aluminium foil subjected to an open flame or a to an extreme heat source, a high percentage of the heat radiation will be reflected by the aluminium; yet, due to the high thermal conductivity of the aluminium, the heat, as it is only prevented by the flame-retardant adhesive, will very quickly act upon the rubber, the temperature of which will immediately begin to rise, so that it will initially start to decompose and then to go up in flames. Dependent of the respective national flame spread tests, an insulating material will obtain in France the fire classification M2, in Germany the fire classification B2 and in Britain the fire classification Class 1 (BS 476: Part 7).

[0017] In the insulating material according to this invention, which is comprising a protective layer consisting of a mat-shaped glass fiber material, being externally coated with a metal or a polymer, and which is connected with the expanded rubber by means of a flame-retardant adhesive, the glass fiber material ensures at the given test conditions determining the fire classification, an unexpectedly long delay in time before the heat reaches the rubber, so that the time before it will come to a release of inflammable gases as well as the time before the rubber will go up in flames may be delayed, as a result of which the insulating material according to this invention will in the fire tests be classified in the fire classes M1 or B1 or Class 0.

[0018] This means that while in the insulating material according to the state of the art, already after a few minutes the flames will start to spread over, it will take in the insulating material according to this invention, under-the same conditions, up to twenty minutes before flames will start to develop.

[0019] By way of example the invention is explained in more detail with reference to the drawings, wherein:

[0020]FIG. 1 shows a schematical side view of a section through an insulating material in the form of a plate and

[0021]FIG. 2 shows a cross section through an insulating material in the form of a tube.

[0022] The insulating material in plate form shown in FIG. 1 comprises a layer 11 of expanded rubber, one surface of which is intended as contact surface 12 with an object to be insulated, and the opposite surface of which is adhesively connected with a protective layer by means of an adhesive layer 16. The protective layer consists of a mat-shaped glass fiber material 14, which is externally provided with a coating 15 of a metal or a polymer.

[0023] The insulating material in tube form shown in FIG. 2 consists of a layer 11 in the form of a hollow cylinder of expanded rubber, which internally has a surface 12 to get into contact with a pipe of corresponding diameter (not shown) to be insulated and an external cylindrical surface 13. The layer 11 of expanded rubber is preferably produced by extrusion. The external cylindrical surface 13 is by means of a an adhesive layer 16 connected with a protective layer, which is formed by a mat-shaped glass fiber material 14, which externally is provided with a coating 15 of a metal or a polymer. The protective layer is extending over the whole circumferential surface. For installation purposes, the tube has a pre-slit area 17, which, inclined to a radial plane, is extending from the inner to the outer side.

[0024] When during an installation at the job site the layer 11 of expanded rubber is wrapped around a pipe (not shown) and the slit 17 of said layer is closed, for example by means of gluing, the protective layer is adhesively secured on the outer circumferential surface of the layer 11 by means of the adhesive 16, wherein in the area of the slit 17, the protective layer may overlap over a part of the circumference, which for example may amount to one third or one quarter of the total circumference.

[0025] Corresponding overlappings of the protective layer may be provided at the front faces of the plate or tube-formed insulating material.

[0026] In the following examples 1 to 4, insulating materials in the form of plates are used. The plates are arranged at a distance of 30 cm in relation to a radiant heater having a capacity of 455 W, which radiating surface of 16 cm² is arranged in parallel to the opposite surface of the plate. The sample of the insulating material is being associated with an external flame having a predefined flame image in a manner such that gases generated through the heating of the sample clearly change the flame image, for example in the form of flaming up.

EXAMPLE 1

[0027] The sample of the insulating material consists of an uncoated plate having a thickness of 25 mm and consisting of expanded acrylonitrile-butadiene rubber with a density of 50 kg/m³.

[0028] The surface exposed to the radiant heater starts very quickly to decompose. After an exposure time to radiation of only 10 s, the external flame starts to flame up due to the formation of gases.

EXAMPLE 2

[0029] The sample of the insulating material is on its one side over the whole area adhesively connected with a non woven glass fiber fabric, which has a thickness of 0,2 to 0,4 mm, and which due to its non-closed area is covering the surface of the plate by 95%. An ignition of the developing gases, for which the flaming-up of the external flame is an indicator, starts after 40 s of exposure to radiation.

EXAMPLE 3

[0030] In the sample of the insulating material of Example 2, an aluminium foil having a thickness of 0,15 mm is adhesively applied on the non woven glass fiber fabric. Even after an exposure time to radiation of five minutes, the external flame is still burning. Hence, a formation of gases has not yet started.

EXAMPLE 4

[0031] In the sample of the insulating material of Example 2, a foil having a thickness of 0,15 mm and consisting of polyvinyl chloride is adhesively applied on the non woven glass fiber fabric. After an exposure time to radiation of five minutes, the external flame starts shortly to flame up at every second, what is to be interpreted in that way that a permanent decomposition has not yet started.

[0032] The preceding examples show that on account of the protective layer of non woven glass fiber fabric and aluminium foil according to Example 3 or of non woven glass fiber fabric and polyvinyl foil according to Example 4, the decomposition or the burning of the expanded acrylonitrile-butadiene rubber is prevented for an unknown, unexpectedly long period of time, as a result of which, the expanded rubber with the protective layer has a very high flame resistance and on account of the protective layer receives an enhanced stability. 

1. Insulating material in the form of plates or tubes comprising an inner layer (11) of plastic foam, the inner surface of which is the contact surface (12) with an object to be insulated, an intermediate layer (14) consisting of a non-woven glass fiber fabric, which layer is adhesively connected with the outer surface (13) of the inner layer (11), and an outer layer (15) being connected with the intermediate layer (14), characterized in that the plastic foam of the inner layer (11) consists of expanded rubber, the non-woven glass fiber fabric of the intermediate layer (14) has a thickness of 0,2 to 0,4 mm, the outer layer (15) is a coating on the non woven glass fabric, which coating is made of a metal or a polymer and is of a thickness of 0,05 to 1 mm, and the inner layer (11) is connected to the intermediate layer (14), which is bearing the coating, by means of a fire-retardant adhesive (16).
 2. Insulating material according to claim 1, characterized in that the metal of the coating consists of aluminium or copper.
 3. Insulating material according to claim 1, characterized in that the polymer of the coating is polyurethane, polyvinyl acetate, polyvinyl chloride or an anorganic or organic silicone compound.
 4. Insulating material according to one of the preceding claims, characterized in that the intermediate layer (14), bearing the outer layer (15), is protruding beyond two opposite sides of the plate or beyond the front faces of the tube or beyond an installation pre-slit (17) running in circumferential direction of the tube, thus allowing for an overlap. 